A PLACIDLY GRAZING ZEBRA suddenly notices the stalking lion in the midstof the Serengeti. Its escape mechanisms heighten: heart rate and vascularpressure increase; blood is diverted to the muscles; and awareness peaks asit springs for its life.1 The presence of aninternal or external force that threatens to disrupt the homeostatic balanceof the organism is perceived as a stressor, and the stress response reflectsa normal adaptation to preserve life. As much as we see ourselves as evolvedand civilized, humans still appear to be superbly adapted to avoid being attackedby wild predators, encounters that fortunately nowadays are relatively infrequentin normal city streets. However, this stress response does not seem to beas appropriate when we are coping with the persistent chronic stressors ofour modern daily lives. We have replaced lions with traffic jams, pollution,and overburdened work environments, but the mechanisms to deal with adversityhave not evolved accordingly. As originally described by Selye,2the pioneer of stress research, the organism has the ability to adapt to acutehomeostatic challenges; however, chronicity leads to exhaustion, distress,and disease.3 Indeed, chronic stress has beenshown to have an adverse effect on health and life expectancy.4-7